A conventional capacitive micromachined ultrasonic transducer (CMUT) device is composed of a membrane over a thin gap that is formed between the membrane and the substrate. The thickness and the lateral dimensions of the membrane as well as the membrane material properties determine the stiffness and the mass of the membrane and therefore, along with the gap height, determine important device parameters such as capacitance, collapse voltage, and frequency of operation. The membrane is tied on the edges to fixed post structures and it flexes in the space that is over the gap.
What is needed is a device that can be manufactured using well-established fabrication techniques of integrated circuits and Micro-Electro-Mechanical Systems, and relies on a substantially translational (piston-like) movement of the top plate as apposed to its deflection or bending in a conventional CMUT to generate a more average displacement of the top plate (and therefore surrounding medium) than in a conventional CMUT.